Sterilization is a process conducted in a specially designed chamber or sterilizer that results in a complete eradication of all viable microorganisms. Sterilization techniques have evolved over time from the traditional methods employing saturated steam at elevated temperature and ethylene oxide gases to more modem techniques, such as those employing liquid, vapor and plasma. Regardless of the technique utilized, the effectiveness of the applied sterilization process must be evaluated especially when sterilizing instruments and devices invasive to the human body.
Several methods are currently available for evaluating the effectiveness of a sterilization process. In some applications, chemical indicators are placed in the sterilization process to verify that the sterilizing medium was present in the correct concentration during the sterilization process. In other applications, process indicators are used to determine if the sterilizing medium was present in the correct concentration for the proper amount of time. Still other applications use biological indicators to determine if the sterilizing medium was sufficient to deactivate a predetermined number of microorganisms on a test strip or contained in the biological indicator.
The biological indicator is typically an absorbent paper strip that contains a predetermined number of microorganisms. The biological indicator is exposed to the sterilizing medium during the sterilization process. At the conclusion of the sterilization process, the biological indicator is placed into a vial containing a growth-promoting medium, i.e., nutrients that aid in the growth of the microorganism. If there are any viable microorganisms on the paper strip that survived the sterilization process, these microorganisms will grow and produce a color change in the growth-promoting medium when properly incubated. The sterilization process is determined to be successful if there is no color change in the growth-promoting medium. In one embodiment, the biological indicator and the growth-promoting medium are disposed in a common housing. The combination of biological indicator and the growth-promoting medium in a common housing is often called a “self-contained biological indicator” (SCBI).
Self-contained biological indicators are generally comprised of a tubular housing having an open end and a closed end. A vial containing a growth-promoting medium is disposed in the housing. A source of microorganisms is also disposed in the housing. The source of microorganisms is typically an absorbent paper strip that has been impregnated with a pre-determined concentration of viable microorganisms. The microorganisms may also be disposed directly on the exterior surface of the vial. A cap is disposed over the open end of the housing. The cap is operable to move between an open position and a closed position. When the cap is in the open position, the interior of the housing is in fluid communication with the environment. In this respect, a sterilizing medium is able to flow into the interior of the housing and contact the source of microorganisms during the sterilization process. The self-contained biological indicator is removed from the chamber of the sterilizer at the end of the process. The cap is then moved to a closed position wherein the interior of the housing is fluidly isolated from the environment. Once sealed, the source of microorganisms is exposed to the growth-promoting medium by fracturing or breaking the vial containing the growth-promoting medium. The SCBI is then incubated at a predetermined temperature for a predetermined duration. At the end of the incubation period, the indicator is evaluated either visually or with a detector to determine whether any microorganisms survived the sterilization process.
As described above, the source of microorganisms is exposed to the growth-promoting medium. In order to expose the source of microorganisms to the growth-promoting medium, the vial must be fractured by the user. Presently, the user must exert a significant amount of force to the housing of the biological indicator to fracture the vial dispose therein. In some instances, the user may use a blunt instrument, e.g., a hammer, to fracture the vial. As a result, significant damage may occur to the biological indicator if excessive force is used. In this respect, present devices are complicated and may require multiple operations to seal and activate the biological indicator.
The present invention provides a device wherein a self-contained biological indicator for determining the efficacy of a sterilization process can be activated.